Power pneumatic



Feb. 25, 1958 'r. F. CHEEK 2,324,477

' POWER PNEUMATIC Filed ma 14, 1953 2 Sheets-Sheet 1 INVEN TOR.

jalbrifafieek w mu u; 63mm 142 i (Jr-Rey POWER PNEUMATIC Tolbert F. Cheek, Gloucester, Mass.

Application May 14, 1953, Serial No. 355,043

7 Claims. (Cl. 8428) This invention relates to pneumatic structures and particularly to pneumatic structures used in automatic musical instruments such as piano players to sound the notes. These are called power or striker pneumatics.

In the use of these pneumatic structures, there is often difiiculty in repairing them and also in determining the cause of trouble when it occurs. In addition, when wood is used, there is often a change in shape with the consequent leakage and interference with the proper operation which sometimes merely reduces the power of the power or striker pneumatic and sometimes causes an actual stoppage. Unless unusual precautions are taken, metal has objectionable qualities from a musical standpoint and also is objectionable because of its weight. With either wood or metal, it is impossible to ever determine the cause of trouble by sight.

The primary object of this invention is the provision of an improved power or striker pneumatic such as is used in an automatic musical instrument to cause it to give forth a note, such as in the lifting of a wippen in a piano.

Another object of the invention is the provision of a power pneumatic, the walls of which are transparent.

A further object of the invention is the provision of an improved power pneumatic wherein is an improved bellows for controlling the opening of a valve from the wind chest to the movable power bellows.

A still further object of the invention is the provision of an improved power pneumatic wherein is a control valve having a flexible air controlling member attached to the stem and contacting the same substantially only at its center. 7

Another and still further object of the invention is the provision of an improved power pneumatic wherein the top of the stem is rounded in shape with a swivel connection at the uppermost place to the flexible valve.

Still another object of the invention is the provision of an improved power or striker pneumatic wherein the entire valve chest is of a plastic or other transparent material which can be worked with tools.

Another and still further object of the invention is the means permitting the valve to have side play.

A still further object of this invention is the provision of an improved power or striker pneumatic having a flexible valve and a valve stem having rotatable and revolving movement relative to the stem and a valve chamber large enough to provide for bodily movement of the stem and valve within the chamber. 1

Other and further objects of the invention will be ap- States Patent parent to those skilled in the art from a reading of the complete specification.

Referring to the drawing where I have illustrated my invention;

Figure l is an assembly view showing my invention in usein place in a piano.

Figure 2 is a partial cross sectional view on the line 22 of Fig. 3.

Figure 3 is a top plan view of a portion of the wind chest and two pneumatics arranged in a pair and having a common double valve chest unit construction.

Figure 4 is a bottom plan view illustrating the fact that the small valve-operating pneumatic may be seen through the lower and upper leaves of the power bellows.

Figure 5 is a partial cross sectional view on the line 2-2 of Figure 3 but showing the valve-operating pneumatic in inflated position to raise the valve to close its atmospheric connection and open the connection from wind chest to the power bellows 28.

Figure 6 is an enlarged detail view of the valve-operating pneumatic and its valve, in operated position as illustrated in Figure 5.

Similar reference characters refer to the same or similar parts throughout the specification and drawing.

In the usual construction of automatic instruments where my invention is particularly adapted for use, there is a vacuum wind chest from which air is exhausted and which extends throughout the length of the keyboard, the keys of which though not in use during automatic use, are usually present. For each note of the piano to be sounded, there is a wippen which is operated by the piano key as in the usual construction of the hand played piano. The wind chest may be made in two or more sections, one above the other in order that the pneumatics for supplying power for the note operation need not be too close together.

Referring to Figure 1 wherein I have illustrated by invention in its place in the assembly of parts, 10 indicates the keybed of the piano which serves as an example in this specification. Pivoted at 11 in the usual manner on the keybed are the piano keys 12 which at their rear ends are provided with adjustable posts 14. These posts 14 are beneath the respective wippens 15 and in position to operate the wippens when the outer ends of the respective keys are depressed. The rear ends of the Wippens 15 are pivoted at the lower ends of the hanger members 16 which are secured to a transverse rail (not shown), which rail extends the length of the keyboard. Pivoted on the wippen 15 is the piano jack 17 which operates the hammer in a well-known manner for sounding the note. A check 18 is securely mounted on each wippen, the checks being in position to contact the piano wires or strings, when the respective notes are sounded. As this piano construction is common in the art and is not a part of my invention, per se, and since this construction is well-known to those skilled in the art, further description will be omitted.

In Figure 1 two wind chest sections 19 and 20 are provided for the support of the pneumatic mechanism for causing automatic operation of the hammers to sound the notes. At the rear of the top wind chest section 19 are provided guides 28 which guide the upper ends of the striker wires 21. The striker wires 21 are provided with screw-threaded leather buttons 22 which are adjusted along the player striker wires 21 to bring about the desired co-action between the pneumatic and the wippen already pointed out.

tion engages the valve seat and when in its lower player striker wire 21.

In the practice of the present invention, the foregoing structure preferably remains in the instrument when the player action to be presently described, is taken out for repair or other reason.

'As the construction of the wind chest section 19 is similar to that ofthe wind chest section 20, and the construction of the player action units are similar, the wind chest section 19 only, with a player action unit attached will be described in detail.

Referring now particularly to Figures 2 to 6, it will be observed that the wind chest section 19 has an opening 19 corresponding to each valve at its forward side for connection to the player'action as will later appear.

The player action comprises essentially two partsthe valve chest and the striker pneumatic bellows which causes the operation of the wippen already described. In the present specification and drawing, the valve chest is illustrated, though not necessarily so, with two valve actions in the same unit. This construction I term a twinunit.

The main body of the twin-unit 25 has two sections, 25 and 25 The section 25 has a pair of chambers, one for each of the valves 26 and the part 25 forms the cover for the valve chest section 25. These valves 26 are respectively secured loosely by the pins 26 to the valve stems 26 It will be noted that the valve stems 26" are rounded, preferably at top and bottom. It has been found that with certain types of valves having the valves and stems rigidly connected together, there has not been provided a sufficient amount of flexibility. This has resulted in a hardening of the valve, which is made of flexible leather, or similar material, and a consequent loss of air pressure through leakage. With the valve herein described, the rounded stem adjacent the valve and the loose connection by the pin 26, a much longer life for the valve is obtained. In order to promote efiicient operation, the valve stem is made preferably of a very light wood and its surface is preferably covered by a coat of graphite. Because of its construction, the valve 26 and its stem 26 does not move successively in exactly the same path, which results in the valve seating at slightly different places in successive operations. This feature has a tendency to prevent hardening of the leather and also prevents the formation of ridges where the valve contacts its seats. The rounded ends of the valve stem 25 also assist in prevention of the undesirable ridges in the surface of the valve.

The valve 26 is located in a valve chamber 25 as This valve when in its upper posiposition, it engages the 'valve seat 25.

The chamber 25 at its rear side is connected with a duct 25 which leads downwardly through the lower wall of the valve chest 25 through the upper wall 28 of the striker pneumatic bellows 28 to the interior of the bellows 28, When the exhaust of the wind chest 19 is connected to the bellows 28, the latter will be collapsed as will later appear.

In the lower portion of the valve chest member 25 is a chamber 25 into which the lower end of the valve stem 26 extends. Beneath the valve stern 25 is a relatively stiif top member 29 of the valve pneumatic for operating the valve stem 26 and the valve 26. The

"member 29 contacts but is not connected to the valve stem 26. Cemented or otherwise secured to the underside of the top member 29 is the valve pneumatic bellows 29. This pneumatic 29 has an opening at its bottom center which is connected to a duct 28 which extends through the upper wall 28 of the striker pneumatic bellows 28. This duct 28* is connected at its forward end'to' the flexible tracker duct tube 30 which connects to an opening in the tracker which is well known in the 'art and for this reason is not illustrated.

A duct 25 connects the chamber 25 with the duct 19 of the wind chest 19 to connect the latter with the chamber 25 In the operation of the striker pneumatic 28 when a note is to be sounded, the pneumatic 29 is flooded with air at atmospheric pressure. This is brought about by the opening of the tracker tube 30 caused by the uncovering of its end by registration of a perforation of the music sheet therewith. This causes the exhaust of the wind chest 19 to permit'the atmospheric pressure of the valve pneumatic 29 to lift the top member 29 with the consequent lifting of the valve stem 26 and its valve member 26.

When the valve 26 is thus lifted, it leaves the valve seat 25 and seats on the seat 25 and thus closes the atmospheric opening in the member 25* coming to rest on its upper seat 25 This action places the chamber 25 Which is in communication with the wind chest 19, in communication with the interior of the bellows 28 through the duct 25 The immediate result is the exhausting of the air from the pneumatic 28 with the atmospheric air causing upward movement of the movable member 28 of the pneumatic 28. This lifting of the movable member 28 in turn causes the lifting arm 28 to raise the player striker wire 21 to lift the wippen extension 15 by the player striker lever with the resultant sounding of a note.

When the perforation of the perforated music sheet closes the tracker duct, it is necessary to return the parts to normal positions so that they will be ready to strike the next required note. In order to bring this about, there is provided a bleed 31. Since the chamber 25 is always connected to to the wind chest 19, the air will immediately be exhausted through the bleed 31 with the result that the valve pneumatic 29 will be deflated. This causes the valve 26 with its valve stem 26 to fall, partially due to the atmospheric pressure on the top of the valve 26 when in its upper position. When the valve 26 releases the atmospheric pressure above the valve seat 25 atmospheric pressure will enter the valve chamber 25, the duct 25 and the interior of the striker pneumatic 28. The movable leaf 28 of the pneumatic 28 will then fall to its normal position, due to the atmospheric pressure admitted thereto.

As already pointed out, the valve construction with the loose connection between the valve 26 and the valve stem 26 at 26- promotes the freedom of the parts which is so important to the long life of the construction as a whole.

There are many features of the present invention which are particularly advantageous for use and maintenance of the power pneumatics. After long use of some types of Pneumatics it has been found that in spite of precautions to obtain the proper kind of wood for use in the construction of the pneumatics, it has been impossible to prevent warpage and cracks. These defects cause the openings at the seams and when cracks occur or the seams open, there is a lossof the exhaust strength with a consequent weakening of the force at which'the pneumatic will strike.

For these reasons and for the reason that from a musical standpoint, metal is objectionable, i have used plastic for the material of construction of the valve chest, its-cover and for the stationary and movable leaves of the power bellows itself. While the material itself makes a better and more lasting construction, it permits also of visual observation for detecting troubles. This is very useful since the unit of one or two 'pneumatics may be easily removed and the parts tested. With the plastic construction, it is possible to easily detect some troubles and remedy them as by reversing the current of airflow if the bleed becomes clogged. But another feature is that with the construction as described herein, there is much less liabilityfor. trouble .to develop and for this reason, it has been found that it is economical to secure the cover 25 on the valve chest member 25 by cement.

While the term plastic has been used, it is understood that any suitable plastic or other transparent workable material may be used in my invention.

One of the reasons why, in the past, it has been necessary to have the valve chest so that it might be opened, has been that the valves have caused trouble and would need replacement after some years of use. In order to make this unnecessary, I have made much improvement in the valve itself. As already pointed out, the valve stem is of very light construction and is secured to the valve by a very light connection and at a single point. The valve itself is not connected to anything at its edges nor do the edges have a backing. Further, the valve stem is rounded at its point of contact with the valve to promote the flexibility and rocking of the valve. The valve is made of prepared leather or some plastic or soft material having a flexible texture. The guide wall for the valve stem 26 which forms the passage between the chambers 25 and 25 forms a space in which the valve stem 26 may move from side to side during operation and which will not guide the valve stem to place the valve in the same place on its valve seats each time it is operated. The valve and its stem may also rotate relatively. This construction all sums up to make a full floating valve which will probably never go through two consecutive cycles in exactly the same manner and seat the valve in exactly the same place.

The power member for operation of the valve to its upper seat 25 and which permits it to drop to its low position on the valve seat 25 is a valve pneumatic which also promotes the sensitive and fast movement of the valve. This valve pneumatic 29 is of a type which is secured in place only at its bottom center immediately around the entrance from the duct 28 and is of the accordion type. This promotes great freedom of action. This pneumatic 29 is made of very thin and lasting flexible material and because of the fact that it has a small relatively stilt top member 29 secured to its upper middle point, the valve 26 by the valve stem 26 is assured of an eflicient operation. It is to be observed that when the valve pneumatic 29 is inflated, it may, in successive operations, lift the valve stem 26 and its valve 26 in a slightly diflerent manner, thus seating the valve differently.

Thus, the construction of the valve pneumatic 29 with its accordion shape and top member 29 the floating action of the stem 26 within the passage between the chambers 25 and 25 the relative movement between the valve stem 26 and top member 29 and the relative movement of the valve 26 and its stem with the point of contact at a small area on the top of the stem, all tend to produce a flexible action for the valve which operates to produce not only an efiicient valve but one which will have a long life.

As already pointed out, the invention is illustrated as having two power pneumatics mounted on a single multiple valve chest. This need not necessarily be the actual construction as more or less may be used. As illustrated, the screw 32 passes through a hole in the valve chest 25 and is screwed into the wall of the wind chest 19. The end of the wind chest section 19 is connected to a header which is not shown but is well known in the art. The header is connected to an exhaust pump which exhausts the air from the wind chest sections 19, 20.

While the invention has been described in connection with a piano, it is to be understood that its use is not confined to piano constructions, and that it may be used in other instruments.

While an embodiment of the invention has been described in detail, it is to be understood that the disclosure is merely illustrative and that modifications and changes may be made without departing from the spirit of the invention and within its scope as claimed.

Having described my invention, what I claim is:

l. A striker pneumatic for use with a wind chest of an automatic musical instrument having a tracker bar, comprising a main pneumatic power bellows, the bellows having relatively stationary and movable members and a flexible member therebetween to provide a collapsible chamber, the stationary member having a valve chest, the valve chest being made of a transparent workable material, a valve in the valve chest to control connection of the pneumatic with the wind chest and having a valve seat, the valve seat being of and on the trans arent workable member, a valve stem having upper and lower hemispherical surfaces, a pin loosely coupling the center of said flexible valve to said upper hemispherical surface, valve operating bellows, a flat rigid member secured to said valve operating bellows, said lower hemispherical surface contacting the side of said flat member opposite to the side to which said valve operating bellows is secured.

2. A striker pneumatic for use with a wind chest of an automatic musical instrument having a tracker bar, comprising a main pneumatic power bellows, the bellows having relatively stationary and movable members and a flexible member therebetween to provide a collapsible chamber, the stationary member having a valve chest, the valve chest being of homogeneous transparent workable material, said chest having an opening in communication with said bellows and forming a valve seat, a valve in said valve chest having coactive engagement with said valve seat in the homogeneous transparent workable material, to control air supply between said bellows and said chest.

3. A construction as described in claim 2 and having its movable member made of homogeneous transparent workable material.

4. A construction as described in claim 2 and having its valve chest provided with a cover made of homogeneous transparent workable material.

5. A construction as described in claim 4 and having its valve chest cover cemented in place.

6. A construction as described in claim 4 and the valve chest having a valve seat integral with the homogeneous transparent material of the cover.

7. A construction as described in claim 5 and having the valve provided with seats on the transparent material at opposite ends of its movement.

References Cited in the file of this patent UNITED STATES PATENTS 857,260 Salyer June 18, 1907 894,007 Hough July 21, 1908 1,638,485 Gustafson Aug. 9, 1927 2,242,418 Cheek May 20, 1941 2,539,146 Loewy Jan. 23, 1951 FOREIGN PATENTS 462,017 Great Britain Mar. 1, 1937 

